Liquid Crystals

Liquid crystals (LCs) are matter in a state that has properties between those of the conventional liquid and those of solid crystal. For instance, a liquid crystal may flow like a liquid, but its molecules may be oriented in a crystal-like way. There are many different types of liquid-crystal phases, which can be distinguished by their different optical properties (such as birefringence). When viewed under a microscope using a polarized light source, different liquid crystal phases will appear to have distinct textures. The contrasting areas in the textures correspond to domains where the liquid-crystal molecules are oriented in different directions. Within a domain, however, the molecules are well ordered. LC materials may not always be in a liquid-crystal phase (just as water may turn into ice or steam).

  • Liquid Crystals Form Nano Rings

    Liquid crystal in a nanopore. A. Zantop/M. Mazza/K. Sentker/P. Huber, Max-Planck Institut für Dynamik und Selbstorganisation/Technische Universität Hamburg (TUHH).

    Quantised self-assembly enables design of materials with novel properties. At DESY's X-ray source PETRA III, scientists have investigated an intriguing form of self-assembly in liquid crystals: When the liquid crystals are filled into cylindrical nanopores and heated, their molecules form ordered rings as they cool – a condition that otherwise does not naturally occur in the material. This behavior allows nanomaterials with new optical and electrical properties, as the team led by Patrick Huber from Hamburg University of Technology (TUHH) report in the journal Physical Review Letters.

  • Neue Materialien für Displays: Forscher verbessern bananenförmige Flüssigkristalle

    Flüssigkristalle sind ein wesentlicher Baustein für Displays von Computern, Handys und Tabletts. So genannte bananenförmige Flüssigkristalle könnten in Zukunft dabei helfen, diese Technologie noch schneller und energiesparender zu machen. Eine internationale Forschergruppe der Martin-Luther-Universität Halle-Wittenberg (MLU) und des Trinity College in Dublin hat nun eine Möglichkeit gefunden, diese großflächig und defektfrei anzuordnen. Das macht das Material auch für Anwendungen in der Elektronik und der Optik denkbar. Die Ergebnisse wurden kürzlich im internationalen Fachjournal "Nature Communications" veröffentlicht.

  • Painting with Crystals

    Using computer simulations, MPI-P scientists can predict the structure of crystals in organic semiconductor layers. © MPI-P

    Semiconductors made of organic materials, e.g. for light-emitting diodes (OLEDs) and solar cells, could replace or supplement silicon-based electronics in the future. The efficiency of such devices depends crucially on the quality of thin layers of such organic semiconductors. These layers are created by coating or printing “inks” that contain the material. Researchers at the Max Planck Institute for Polymer Research (MPI-P) have developed a computer model that predicts the quality of such layers as a function of processing conditions, such as the drying time of the ink or the speed coating. This model aims to accelerate the time-consuming approaches for process and product optimization.

  • Porous crystalline materials: TU Graz researcher shows method for controlled growth

    Porous cystalls called MOFs on a comparatively large surface area of one square centimetre. © Nature Materials 2016 Falcaro

    Microporous crystals (MOFs) have a great potential as functional materials of the future. Paolo Falcaro of TU Graz et al demonstrate in Nature Materials how the growth of MOFs can be precisely controlled on a large scale. Porous crystals called metal-organic frameworks (MOFs) consist of metallic intersections with organic molecules as connecting elements. Thanks to their high porosity, MOFs have an extremely large surface area. A teaspoonful of MOFs has the same surface area as a football pitch. These countless pores situated in an extremely small space offer room for “guests” and can, for example, be used for gas storage or as “molecular gate” for separation of chemicals.

  • Significantly more productivity in USP lasers

    With the hybrid systems composed of freely programmable multi-beam optics and galvo scanners, a laser beam can be split into any number of beamlets. © Fraunhofer ILT, Aachen, Germany / Volker Lannert.

    In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

  • Sonnenlicht direkt in mechanische Arbeit umwandeln - neu entwickelte Materialien führen zu ersten Erfolgen

    Ein Team von Forschern der Humboldt-Universität zu Berlin und der Technischen Universität Eindhoven in den Niederlanden hat dünne Plastikfilme entwickelt, die sich kontinuierlich im Sonnenlicht bewegen. Derartige Materialien, die die Energie des Sonnenlichtes direkt in Bewegung umwandeln können, sind vielversprechende Kandidaten für die Entwicklung von solar getriebenen aktiven Oberflächen, wie z.B. in selbstreinigenden Fenstern. Die Ergebnisse dieser Studie wurden jetzt in Nature Communications veröffentlicht.

  • Spin liquids − back to the roots

    Sketch of Anderson's resonating valence bond state formed by localized spins shown in green. The pair of opposite spins ("valence bond") is highlighted by a yellow oval. © Universität Augsburg, EP VI/EKM

    Researchers from Augsburg, Oxford, and Nanjing report in Nature Communications on a neutron experiment exposing experimental signatures of a low-temperature state predicted 44 years ago

    Since 1973, Anderson's resonating valence bond model remains a paradigm for microscopic description of quantum spin liquids in frustrated magnets. It is of fundamental interest as a building unit for more complex quantum-mechanically entangled states that can be used in quantum computing. Researchers from the Chair of Experimental Physics VI/EKM report in Nature Communications first experimental signatures of excitations from this fundamental state exposed by a neutron-scattering study performed in collaboration with Rutherford Appleton Laboratory in Oxford and Renmin University of China.